Uttlesford District Council has now issued a warning of the danger of entering the inside of the castle after the out-of-bounds 12th century momunment was de-faced with what appears to be spray paint.

Meanwhile, Saffron Walden mayor, Cllr Keith Eden, said: “Graffiti isn’t a big problem here but we do get it from time to time. It is always distressing and it causes more irritation than the perpetrators think it does. On an ancient monument it is disgraceful.

“The trouble is how to catch the perpetrators and name and shame them.”

It is unclear when the act took place, but the Reporter was alerted to the graffiti after Kevin Taylor tweeted about it at the end of last week.

Andrew Taylor, Uttlesford District Council’s assistant director planning and building control, said the authority was investigating the damage and will be consulting with specialist companies on how it can be removed.

He added: “Since the castle is a Grade I listed building, it will require specialist equipment to remove the graffiti.

“We want to stress that it is very dangerous for anyone to enter the inside section of the castle – it is an unstable structure and there is a risk of falling masonry.”

The council has a long-term goal to open the castle for more general use and is preparing to spend hundreds of thousands of pounds refurbishing it. Critical work to stabilise some of the pier walls was carried out last June in the first phase to make the site a more prominent tourism attraction.

There are currently no fixed views on its future use, although ideas being considered include removing part of the external wall around the site and installing up-lighting to emphasise the monument.